Clamp and drill jig



Aug. 15, 1939. Y K LL 2,169,328

CLAMP AND DRILL JIG Filed Dec. 22, 1937 2 Sheets-Sheet l INVENTOR. Mam/e55: BY yousiow s/ekea AT RNEY.

Aug. 15, 1939. SEKELLA 2,169,328

CLAMP AND DRILL JIG Filed Dec. 22, 1937 2 Sheets-Sheet 2 di luwlnmli INVENT OR.

BY gmS/mlw 1 Patented Aug. 15, 1939 UNITED STATES PATENT OFFICE CLAMP AND DRILL JIG Delaware Application December 22, 1937, Serial No. 181,190

5 Claims.

The present invention relates to a clamp and drill jig for starter drives and more particularly to a device for holding a commercial form of starter drive With the drive spring in compressed condition and the drive head located in position to be drilled for a through drive pin.

In servicing engine starter drives of the type illustrated in the patent to Sekella No. 2,062,430, it is necessary in order to remove the drive from the motor shaft that the drive spring be compressed to expose the locking pin for the drive head. Moreover, it is sometimes desired to connect a drive head of this type with its armature shaft by means of a through pin instead of the key illustrated, and in such case it is preferable that the pin be located uniformly with respect to the keyway and the flattened surfaces of the drive head.

It is an object of the present invention to provide a novel clamp for holding a starter drive to facilitate service operations thereon.

It is another object to provide such a device which holds the drive spring compressed so that the drive head protrudes and exposes the anchorlng means therefor.

It is a further object to provide such a device which is arranged to function as a jig for holding the drive in position for drilling the drive head and installing a locking device.

It is another object to provide such a device in which the drill jig holds the drive head in a particular angular position so as to locate the drilled opening in predetermined relation to the features of the head.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawings in Which:

Fig. l is a perspective view of a preferred embodiment of the invention operatively engaging and holding a commercial form of starter drive;

Fig. 2 is an end view of the device in use as a drill jig;

Fig. 3 is a side view of the device with a drive mounted therein in position for servicing;

Fig. 4 is a perspective view of the clamp alone; and

Fig. 5 is an end view of the clamp with a drive of the keyless type mounted the-rein.

Referring first to Fig. 1 of the drawings, it will be seen that the clamping device indicated generally by numeral 1 comp-rises a flat base portion 2 with upstanding pairs of arms 3, 4, and 5, 5, each pair of arms being arranged to straddle the driivng and driven heads 1 and 8 respectively of a starter drive indicated generally at 9, and the pairs of arms 3, 4 and 5, B being so spaced longitudinally as to hold the drive spring 1 I compressed substantially solidly between the anchor plates l2 and I3 of the drive.

Referring to Fig. 3 of the drawings, it will be noted that the starter drive comprises a drive head I which is to be rigidly connected to a driving shaft M, a driven head 8 forming part of a screw shaft l0 and connected to the driving head through the torsion and compression spring H by means of anchor plates [2, [3 which are slidably but non-rotatably mounted on the driving and driven heads respectively. Expansion of the spring H is limited by a split ring I5 on the driving head 1 and a flange I6 on the driven head 8.

A pinion I! slidably mounted on the driving shaft I4 is adapted to be moved into mesh with an engine gear and to be rotated from the screw shaft Ii] by means of a nut l8 mounted on the screw shaft and connected by a barrel l9 to the pinion. Longitudinal motion of the nut I8 in the meshing direction is limited by a stop nut 2| rigid with the drivng shaft so that rotation of the screw shaft while the pinion and nut are held from rotation causes the screw shaft to move backward and compress the spring i I.

When it is desired to service the drive, advantage is taken of this screw jack action to compress the spring II by applying torque to the driving head while holding the pinion and barrel from rotation. When the spring has been thus compressed, the drive is inserted in the clamp with the arms 3, 4 bearing against the anchor plate [2 and the arms 5, 6 bearing against a shoulder 22 at the back of the flange 16 on the driven head 8. The spring II is thus held compressed, and the driving head I permitted to protrude so as to expose the means for anchoring the driving head on the shaft Hi.

There are in commercial use two types of anchorages for this driving head which are necessary to be removed when servicing the drives in the field. In the first type, as illustrated in Fig, 3, torque is transmitted from the shaft [4 to the driving head I by means of a key 23 usually of the Woodruff type, and the longitudinal position of the driving head on the shaft is determined by a stud 24 having a pilot extending into an aperture in the shaft. In this case the keyway 25 (Fig. 2) in the driving head is located between the flattened portions 26 and 21 of the head which provide the non-rotatable connection between the head and its anchor plate I2. The

opening 28 (Fig. 1) for the stud is located substantially at right angles to the keyway 25 and is also spaced from the flattened portion 26 so as to secure the full thickness of the metal of the driving head.

In the second form of anchorage, both torsion and longitudinal stresses are taken by an anchor pin 29 (Fig. 5) passing directly through the driving head 7 and the driving shaft 14 midway between the flattened portions 26, 21 of the drivin: head.

It is frequently desired when servicing drives in the field to change from the key type of anchorage to the pin type, and the clamp constituting the subject-matter of the present invention is hot only adapted to facilitate servicing drives with each type of anchorage but is also particularly constructed to facilitate changing the anchorage from the key type to the pin type.

Fig. 1 illustrates a drive with the key type anchorage mounted in the clamp with the driving head 1 exposed and the key and stud removed from the keyway 25 and opening 28. It will be noted that an opening 3| is provided in the arm 3, said opening providing a shoulder 32. The outturned end 33 of the drive spring engages the shoulder 32, and said shoulder is so located as to position the opening 28 vertically with respect to the base 2 of the clamp.

The sides 34, 35, 36 and 3'! of the arms 3, 4, 5 and 6 respectively are parallel to each other and arranged vertically with respect to the base 2 of the clamp whereby the clamp may be mounted in the jaws 38, 39 of a vise as indicated in Fig. 2,

' and the clamp then serves as a drill jig, permitting the intrcduction of a drill 4| through the opening 28 of the drive head I for the purpose of drilling the driving shaft [4 when located therein and continuing the opening 28 through the opposite side of the driving head as indicated at 28 in Figs. 1 and 2.

When it is desired to service and remount a drive of the type having the pin anchorage, the same procedure is followed, but the opening for the pin 29 is located as shown in Fig. 5 by means of a shoulder 42 at the upper end of the opening 3| whereby the pin opening is vertically positioned. The clamp thus forms a drill jig for holding the drive while drilling a new armature shaft in the same manner as previously described. A vertical opening 43 (Fig. 4) is preferably provided between the arms 3 and 4 to provide a runout for the drill.

Although but one embodiment of the invention has been shown and described in detail, it will be understood that other embodiments are possible and various changes may be made in the design and arrangement of the parts without departing from the spirit of the invention as defined in the claims appended hereto.

What is claimed is:

l. A clamp for starter drives including a base portion with spaced bifurcated flanges extending therefrom in generally parallel relation and having substantially parallel edges adapted for reception in a clamping support, the bifurcations of the flanges being so formed and spaced as to straddle and compress a yielding element of the drive, one of said flanges having abutment means cooperating with a projection on the drive for orienting the drive angularly therein.

2. A clamp for starter drives including a base portion with spaced bifurcated flanges extending therefrom in generally parallel relation and having substantially parallel edges adapted for reception in a clamping support, the bifurcations of the flanges being so formed and spaced as to straddle and compress a yielding element of the drive, one of said flanges having a cut-away portion providing shoulders adapted to receive and locate a projecting portion of a drive spring, and being further cut away to provide clearance for a drill traversing a drive head located therein in a predetermined angular position.

3. A clamping member for a starter drive, which drive includes a driving head, a driven head and means including a torsion spring having a slidable but non-rotatable connection with said heads, said clamping member including spaced bifurcated flanges adapted to straddle said heads and hold the spring compressed therebetween while permitting sliding movement of the driving head relative thereto.

4. A clamping member for a starter drive, which drive includes a driving head, a driven head and means including a torsion spring having a sldiable but non-rotatable connection with said heads, said clamping member including a bifurcated flange adapted to interlock with the driven head, and a parallel bifurcated flange arranged to slidably engage the driving head and hold the spring compressed therebetween, said latter flange having abutment means cooperating with a projection on said drive for angularly orienting the drive.

5. A clamping member for a starter drive, which drive includes a driving head, a driven head and means including a torsion spring having a slidable but non-rotatable connection with said heads, said clamping member including a bifurcated flange adapted to interlock with the driven head, and a parallel bifurcated flange arranged to slidably engage the driving head and hold the spring compressed therebetween, said latter flange having a shoulder adapted to engage an outturned end of the spring and thus define the angular position of the drive in the clamp.

YOUSTON SEKELLA. 

